Magnetic body and process of making same



Sept. 18, 1934. MA|ER I 1,974,079

MAGNETIC BODY AND PROCESS OF MAKING SAME Filed June 14, 1953 FIG.

INVENTOR K. MA IER A T TORNEV Patented Sept. 18, 1934 UNITED STATESPATENT OFFICE Karl Maier,

assignor to AME Berlin-Charlottenburg, Germany, Siemens and HalskeAktiengesellschaft, Siemensstadt, near Berlin, Germany, a

company of Germany Application June 14, 1933, Serial No. 675,695 InGermany June 25, 1932 6 Claims. (01. 175-21) This invention relates tomagnetic bodies and particularly to magnetic cores, sheaths, etc. forelectrical transmission apparatus such as is used in communicationsystems, for example, loading coils, transformers and the like, andprocesses for making same.

An object of the invention is to produce a magnetic body having improvedmagnetic characteristics.

As is well known magnetic alloys of the nickeliron group because oftheir desirable magnetic characteristics are preferred as magneticmaterial for use in magnetic cores for loading coils and transformers.These alloys are commonly made by melting together the individual metalsto form an alloy which is then brought into the desired form by casting,rolling and the like. In another process used heretofore the desiredalloy is formed by mixing the individual materials in powder form andsubjecting the mixture to a heat treatment. The material obtained inthis way, which is characterized by a granular structure, has a highstability at relativelylow permeability. In most fields of the electricart, however, the requirement of high stability gives way to that ofhigh permeability, for as is well known, when employing a material ofhigh permeability, the size of the apparatus manufactured can be reducedand thus a saving in material obtained.

In accordance with the process of the invention a material may beobtained which is remarkable for high permeability. Furthermore, theprocess has the advantage that in spite of the same basic materials inthe construction of the metal block from these. materials thepermeability can be very easily adapted to the desired object of use. Inaccordance with the invention these advantages are attained by buildingup a magnetic body comprising several layers of different magneticmaterials and then subjecting the body to a heat treatment so that thereis a partial alloying and sintering together of the individual layers ofmaterial. The stratification of the materials thereby takes place insuch a way that the lines of force preponderantly fall in the directionof the cohering metal structure. The formation of layers of theindividual materials may be carried out in several different ways. Oneway is to use sheets of different material which are placed on eachother or to place intermediate layers of pulverized or flat structure ofmagnetic conducting or even non-conducting material between theindividual sheets of the same or different magnetic materials. Insteadof the mechanical layer formation it is also possible to apply theindividual layers successively on to acarrier material by electrolyticmeans. A layer formation can also be carried out by means of metalcomminution. For the sake of completeness it may also be mentioned thatthe desired layer formation can also be obtained 'by the pouring on ofdifferent metals.

The nature of the invention and its advantages will be clear from thefollowing detailed description thereof when read in connection with theaccompanying drawing, Figsrl to 3 of which illustrate different forms ofmagnetic bodies which may be constructed by the process of theinvention.

Fig. 1 shows a layer formation in which the 79 formation takes place bypurely mechanical means by the superposition of different sheets. Such aformation is preferably suitable for apparatus of the alternatingcurrent art. The structure shown in Fig. 1 differs from the structuresof the prior art which comprise superposed sheets I, II, III etc., ofmagnetic material of uniform composition separated by paper insulatingmaterial, in that the sheets I, II, III etc., in turn are constructed ofindividual layers indicated in the figure by the layers designated withthe Arabic numerals l, 2, 3, 4 and 5, and which may consist of materialsof difierent magnetic conductivity. Layers of non-conducting materialmay also be included if necessary; for example, the sheets I may be ironplates of the same composition; the sheets 2 and 4 may be, for example,nickel plates of different compositions, and sheet 3 a plate ofdifferent composition, for example, a highly silicized iron plate. Thelayer 5 represents a peculiarity insofar as the material of this layeris only distributed in lumps between the layer materials 1 and 3. Thisstep may be employed with advantage if materials 1 and 3 alone are notsufficient to produce the desired alloy. The bundle of sheets 95constructed in this manner is subjected to a heat treatment to whichmaybe added a further mechanical treatment, for example, rolling. Thebundle may be subjected to mechanical processes such as rolling beforethe heat treatment in order 10 to establish a closer contact of thelayers.

Fig. 2 shows a further example of a layer construction. The layerdesignated as 6 represents the main material, on whose surfaces areproduced thin coatings '7 of another material to pro- 5 vide additionallayers. The coatings 7 may be applied by electrolytic means, by sprayingfinely divided metal dust on the surfaces of the layer 6 or by pouring amolten material of the desired composition on to the layer 6.

For the construction of a magnetic body, such as, a laminated disc, ringtransformer, as shown in Fig. 3, thin elementary discs of the basicmaterials designated 8 and 9 may first be superposed ment to produce apartial alloying and sintering together of adjacent layers.

2. A magnetic body formed by superposing a plurality of sheetsrespectively comprising nickel and iron so as to produce alternatelayers of nickel and iron, and subjecting the whole to heat treatment toproduce partial alloying and sintering together of the nickel and iron.

3. A magnetic body formed by superposing a plurality of sheets andpulverized particles of different magnetic materials, and subjecting thewhole to heat treatment to produce partial alloying and sinteringtogether of adjacent layers.

4. A magnetic body formed by superposing a plurality of sheets ordifferent magnetic materials, compressing the body so formed to produceclose contact between the several layers, and heat treating the whole toproduce partial alloying and sintering together of adjacent layers.

5. A magnetic body formed by superposing a plurality of plates ofdifferent magnetic materials, heat treating the superposed plates toproduce partial alloying and sintering together of the differentmagnetic materials and subjecting the resultant body to mechanicaltreatment to improve its magnetic and mechanical characteristics.

6. The process of producing a magnetic body which consists insuperposing sheets of different magnetic materials, and subjecting theresulting product to heat treatment to cause partial alloying andsintering together of adjacent layers while subjecting it tomechanicaltreatment to bring the layers closer together.

-- KARL MAIER.

